1. Field of the Invention
The present invention relates to a laminated structure consisting of a novel organic-inorganic hybrid material and an optical waveguide, which are useful for a board for electrical wiring, materials for mechanical parts, an antireflection coating, various coating materials like a surface protection coating, an optical communication device such as an optical transmitter and receiver module and an optical switch, optical devices having a structure of an optical transmission line such as an optical waveguide and an optical fiber, eyeglasses, an optical lens, an optical filter, a diffraction grating, a light guiding plate, an interferometer, an optical coupler, an optical coupler/branching filter, an optical sensor, a holographic optical element, another materials for optical parts, a photovoltaic device, a contact lens and a medical artificial tissue.
2. Related Art
In electronic components, optical components or elements thereof, there are occasions when a laminated structure formed by laminating layers, each of which is formed from a different material in properties, formed from at least two materials is used. For example, in an optical waveguide which has a function to confine and propagate optical energy, the laminated structure is prepared by laminating two or more layers, each of which is formed from a material having a different refractive index.
The optical waveguides are used in a wide variety of optical system devices of optical integrated circuits, optical fiber communication and the like. As the material of the optical waveguide, organic-inorganic hybrid materials having high optical transparency are studied.
In Japanese Patent Laid-Open No. 356722(2000), there is disclosed a method in which a groove is formed in a quartz substrate, a sol-gel solution of an organic-inorganic hybrid material is impregnated into the groove, and then the sol-gel solution is cured by ultraviolet irradiation to form a core.
FIG. 15 is a sectional view showing an example of the method in which a groove is formed in a substrate and an organic-inorganic hybrid material is impregnated into this groove to form a core.
As shown in FIG. 15(a), the organic-inorganic hybrid material 2 is filled so as to bury the inside of a groove 1a of a substrate 1 in which the groove 1a is formed. Next, after the organic-inorganic hybrid material 2 is heated to be dried, an excessive organic-inorganic hybrid material 2 is eliminated along a top surface of the substrate 1 as shown in FIG. 15 (b). Then, as shown in FIG. 15(c), an upper clad layer 3 is provided on the core layer 2 and the substrate 1 to complete the optical waveguide.
However, there was a problem that in eliminating the excessive organic-inorganic hybrid material 2 by lapping, flaws due to lapping remain on the top surface of the core layer 2, and when light is propagated within the core 2, the propagated light is scattered due to the flaws and propagation losses of light is generated.